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  1 / 34 MEDLINE  
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PMID:27793086
Autor:Lambert MR; Skelly DK; Ezaz T
Endereço:School of Forestry and Environmental Studies, Yale University, Greeley Memorial Lab, 370 Prospect St, New Haven, CT, 06511, USA. max.lambert@yale.edu.
Título:Sex-linked markers in the North American green frog (Rana clamitans) developed using DArTseq provide early insight into sex chromosome evolution.
Fonte:BMC Genomics; 17(1):844, 2016 10 28.
ISSN:1471-2164
País de publicação:England
Idioma:eng
Resumo:BACKGROUND: The extent to which sex reversal is associated with transitions in sex determining systems (XX-XY, ZZ-ZW, etc.) or abnormal sexual differentiation is predominantly unexplored in amphibians. This is in large part because most amphibian taxa have homomorphic sex chromosomes, which has traditionally made it challenging to identify discordance between phenotypic and genetic sex in amphibians, despite all amphibians having a genetic component to sex determination. Recent advances in molecular techniques such as genome complexity reduction and high throughput sequencing present a valuable avenue for furthering our understanding of sex determination in amphibians and other taxa with homomorphic sex chromosomes like many fish and reptiles. RESULTS: We use DArTseq as a novel approach to identify sex-linked markers in the North American green frog (Rana clamitans melanota) using lab-reared tadpoles as well as wild-caught adults from seven ponds either in undeveloped, forested habitats or suburban ponds known to be subject to contamination by anthropogenic chemicals. The DArTseq methodology identified 13 sex-linked SNP loci and eight presence-absence loci associated with males, indicating an XX-XY system. Both alleles from a single locus show partial high sequence homology to Dmrt1, a gene linked to sex determination and differentiation throughout Metazoa. Two other loci have sequence similarities to regions of the chimpanzee and human X-chromosome as well as the chicken Z-chromosome. Several loci also show geographic variation in sex-linkage, possibly indicating sex chromosome recombination. While all loci are statistically sex-linked, they show varying degrees of female heterozygosity and male homozygosity, providing further evidence that some markers are on regions of the sex chromosomes undergoing higher rates of recombination and therefore further apart from the putative sex determining locus. CONCLUSION: The ease of the DArTseq platform provides a useful avenue for future research on sex reversal and sex chromosome evolution in vertebrates, particularly for non-model species with homomorphic or cryptic or nascent sex chromosomes.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Genetic Markers)


  2 / 34 MEDLINE  
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PMID:27667807
Autor:Julian JT; Gould VA; Glenney GW; Brooks RP
Endereço:Division of Mathematics and Natural Science, Penn State University-Altoona College, 3000 Ivyside Park, Altoona, PA 16601,USA.
Título:Seasonal infection rates of Batrachochytrium dendrobatidis in populations of northern green frog Lithobates clamitans melanota tadpoles.
Fonte:Dis Aquat Organ; 121(2):97-104, 2016 09 26.
ISSN:0177-5103
País de publicação:Germany
Idioma:eng
Resumo:Few studies have documented seasonal variation of Batrachochytrium dendrobatidis (Bd) infection rates in larval amphibians. We identified 4 natural populations of northern green frogs Lithobates clamitans melanota in Pennsylvania (USA) that contained Bd-infected tadpoles during post-wintering collections in May and June, after hibernating tadpoles had overwintered in wetlands. However, we failed to detect infected tadpoles at those wetlands when pre-wintering collections were made in late July through early September. We observed 2 cohorts of tadpoles that appeared to lack Bd-infected individuals in pre-wintering collections, yet contained Bd-infected individuals the following spring. We also observed 4 cohorts of pre-wintering tadpoles that were Bd-free, even though post-wintering tadpoles collected earlier in the year were infected with Bd. Our results suggest that tadpoles either reduce Bd infections during the summer months, and/or infections proliferate sometime prior to (or shortly after) tadpoles emerge from hibernation. It is unlikely that pre-wintering tadpoles were too small to detect Bd zoospores because (1) there was no correlation between Bd zoospore levels and tadpole size or stage, and (2) size was not a significant predictor of infection status. These results suggest that, while sampling larvae can be an effective means of collecting large sample sizes, investigators in our Mid-Atlantic region should conduct sampling by early summer to maximize the chances of detecting Bd. Further research is warranted to determine whether wetland topography and warm, shallow microhabitats within wetlands contribute to a population's ability to drastically reduce Bd prevalence prior to overwintering at ponds.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T


  3 / 34 MEDLINE  
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PMID:27220200
Autor:Hossie TJ; Murray DL
Título:Spatial arrangement of prey affects the shape of ratio-dependent functional response in strongly antagonistic predators.
Fonte:Ecology; 97(4):834-41, 2016 Apr.
ISSN:0012-9658
País de publicação:United States
Idioma:eng
Resumo:Predators play a key role in shaping natural ecosystems, and understanding the factors that influence a predator's kill rate is central to predicting predator-prey dynamics. While prey density has a well-established effect on predation, it is increasingly apparent that predator density also can critically influence predator kill rates. The effects of both prey and predator density on the functional response will, however, be determined in part by their distribution on the landscape. To examine this complex relationship we experimentally manipulated prey density, predator density, and prey distribution using a tadpole (prey)-dragonfly nymph (predator) system. Predation was strongly ratio-dependent irrespective of prey distribution, but the shape of the functional response changed from hyperbolic to sigmoidal when prey were clumped in space. This sigmoidal functional response reflected a relatively strong negative effect of predator interference on kill rates at low prey: predator ratios when prey were clumped. Prey aggregation also appeared to promote stabilizing density-dependent intraguild predation in our system. We conclude that systems with highly antagonistic predators and patchily distributed prey are more likely to experience stable dynamics, and that our understanding of the functional response will be improved by research that examines directly the mechanisms generating interference.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T


  4 / 34 MEDLINE  
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PMID:27194039
Autor:Gray KT; Escobar AM; Schaeffer PJ; Mineo PM; Berner NJ
Endereço:Department of Biology, University of the South, Sewanee, Tennessee.
Título:Thermal Acclimatization in Overwintering Tadpoles of the Green Frog, Lithobates clamitans (Latreille, 1801).
Fonte:J Exp Zool A Ecol Genet Physiol; 325(5):285-93, 2016 Jun.
ISSN:1932-5231
País de publicação:United States
Idioma:eng
Resumo:Seasonal acclimatization permits organisms to maintain function in the face of environmental change. Tadpoles of the green frog (Lithobates clamitans) overwinter as tadpoles in much of their range. Because they are active in winter, we hypothesized that green frog tadpoles would display acclimatization of metabolic and locomotor function. We collected tadpoles in Sewanee, Tennessee (35.2°N) in winter and summer. Tadpoles collected during each season were tested at both winter (8°C) and summer (26°C) temperatures. Winter tadpoles were able to maintain swimming performance at both temperatures, whereas swimming performance decreased at cold temperatures in summer tadpoles. There was no evidence for seasonal acclimatization of whole-animal metabolic rate. Although whole-animal metabolic acclimatization was not observed, the activities of cytochrome c oxidase, citrate synthase, and lactate dehydrogenase measured in skeletal muscle homogenates showed higher activity in winter-acclimatized tadpoles indicating compensation for temperature. Further, the composition of muscle membranes of winter tadpoles had less saturated and more monounsaturated fatty acids and a higher ω-3 balance, unsaturation index, and peroxidation index than summer tadpoles. These data indicate that reversible phenotypic plasticity of thermal physiology occurs in larval green frog tadpoles. They appear to compensate for colder temperatures to maintain burst-swimming velocity and the ability to escape predators without the cost of maintaining a constant, higher standard metabolic rate in the winter.
Tipo de publicação: JOURNAL ARTICLE


  5 / 34 MEDLINE  
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PMID:27157807
Autor:He Z; Liu B; Wang X; Bian M; He R; Yan J; Zhong M; Zhao X; Liu X
Endereço:Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China; Department of Molecular, Cell & Developmental Biology, University of California, Los Angeles, CA 90095, USA.
Título:Construction and Validation of a Dual-Transgene Vector System for Stable Transformation in Plants.
Fonte:J Genet Genomics; 43(4):199-207, 2016 Apr 20.
ISSN:1673-8527
País de publicação:China
Idioma:eng
Resumo:In this study, we constructed dual-transgene vectors (pDT1, pDT7, and pDT7G) that simultaneously co-expressed two genes in plants. ACTIN2 and UBQ10 promoters were used to control the expression of these two genes. The 4×Myc, 3×HA, and 3×Flag reporter genes allowed for the convenient identification of a tunable co-expression system in plants, whereas the dexamethasone (Dex) inducible reporter gene C-terminus of the glucocorticoid receptor (cGR) provided Dex-dependent translocation of the fusion gene between the nucleus and cytoplasm. The function of pDT vectors was validated using four pairwise genes in Nicotiana benthamiana or Arabidopsis thaliana. The co-expression efficiency of two genes from the pDT1 and pDT7G vectors was 35% and 42%, respectively, which ensured the generation of sufficient transgenic materials. These pDT vectors are simple, reliable, efficient, and time-saving tools for the co-expression of two genes through a single transformation event and can be used in the study of protein-protein interactions or multi-component complexes.
Tipo de publicação: JOURNAL ARTICLE


  6 / 34 MEDLINE  
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PMID:27040618
Autor:Altman KA; Paull SH; Johnson PT; Golembieski MN; Stephens JP; LaFonte BE; Raffel TR
Endereço:Department of Biological Sciences, Oakland University, Rochester, MI, 48309, USA.
Título:Host and parasite thermal acclimation responses depend on the stage of infection.
Fonte:J Anim Ecol; 85(4):1014-24, 2016 Jul.
ISSN:1365-2656
País de publicação:England
Idioma:eng
Resumo:Global climate change is expected to alter patterns of temperature variability, which could influence species interactions including parasitism. Species interactions can be difficult to predict in variable-temperature environments because of thermal acclimation responses, i.e. physiological changes that allow organisms to adjust to a new temperature following a temperature shift. The goal of this study was to determine how thermal acclimation influences host resistance to infection and to test for parasite acclimation responses, which might differ from host responses in important ways. We tested predictions of three, non-mutually exclusive hypotheses regarding thermal acclimation effects on infection of green frog tadpoles (Lithobates clamitans) by the trematode parasite Ribeiroia ondatrae with fully replicated controlled-temperature experiments. Trematodes or tadpoles were independently acclimated to a range of 'acclimation temperatures' prior to shifting them to new 'performance temperatures' for experimental infections. Trematodes that were acclimated to intermediate temperatures (19-22 °C) had greater encystment success across temperatures than either cold- or warm-acclimated trematodes. However, host acclimation responses varied depending on the stage of infection (encystment vs. clearance): warm- (22-28 °C) and cold-acclimated (13-19 °C) tadpoles had fewer parasites encyst at warm and cold performance temperatures, respectively, whereas intermediate-acclimated tadpoles (19-25 °C) cleared the greatest proportion of parasites in the week following exposure. These results suggest that tadpoles use different immune mechanisms to resist different stages of trematode infection, and that each set of mechanisms has unique responses to temperature variability. Our results highlight the importance of considering thermal responses of both parasites and hosts when predicting disease patterns in variable-temperature environments.
Tipo de publicação: JOURNAL ARTICLE


  7 / 34 MEDLINE  
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PMID:26912042
Autor:Rothermel BB; Miller DL; Travis ER; Gonynor McGuire JL; Jensen JB; Yabsley MJ
Endereço:Archbold Biological Station, Venus, Florida 33960, USA.
Título:Disease dynamics of red-spotted newts and their anuran prey in a montane pond community.
Fonte:Dis Aquat Organ; 118(2):113-27, 2016 Feb 25.
ISSN:0177-5103
País de publicação:Germany
Idioma:eng
Resumo:Long-term monitoring of amphibians is needed to clarify population-level effects of ranaviruses (Rv) and the fungal pathogen Batrachochytrium dendrobatidis (Bd). We investigated disease dynamics of co-occurring amphibian species and potential demographic consequences of Rv and Bd infections at a montane site in the Southern Appalachians, Georgia, USA. Our 3-yr study was unique in combining disease surveillance with intensive population monitoring at a site where both pathogens are present. We detected sub-clinical Bd infections in larval and adult red-spotted newts Notophthalmus viridescens viridescens, but found no effect of Bd on body condition of adult newts. Bd infections also occurred in larvae of 5 anuran species that bred in our fishless study pond, and we detected co-infections with Bd and Rv in adult newts and larval green frogs Lithobates clamitans. However, all mortality and clinical signs in adult newts and larval anurans were most consistent with ranaviral disease, including a die-off of larval wood frogs Lithobates sylvaticus in small fish ponds located near our main study pond. During 2 yr of drift fence monitoring, we documented high juvenile production in newts, green frogs and American bullfrogs L. catesbeianus, but saw no evidence of juvenile recruitment in wood frogs. Larvae of this susceptible species may have suffered high mortality in the presence of both Rv and predators. Our findings were generally consistent with results of Rv-exposure experiments and support the purported role of red-spotted newts, green frogs, and American bullfrogs as common reservoirs for Bd and/or Rv in permanent and semi-permanent wetlands.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.


  8 / 34 MEDLINE  
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PMID:26873311
Autor:Rebollar EA; Simonetti SJ; Shoemaker WR; Harris RN
Endereço:Department of Biology, James Madison University, Harrisonburg, Virginia, USAUSDA Forest Products Laboratory ea.rebollar@gmail.com.
Título:Direct and Indirect Horizontal Transmission of the Antifungal Probiotic Bacterium Janthinobacterium lividum on Green Frog (Lithobates clamitans) Tadpoles.
Fonte:Appl Environ Microbiol; 82(8):2457-66, 2016 Apr.
ISSN:1098-5336
País de publicação:United States
Idioma:eng
Resumo:Amphibian populations worldwide are being threatened by the disease chytridiomycosis, which is caused by Batrachochytrium dendrobatidis To mitigate the effects of B. dendrobatidis, bioaugmentation of antifungal bacteria has been shown to be a promising strategy. One way to implement bioaugmentation is through indirect horizontal transmission, defined as the transfer of bacteria from a host to the environment and to another host. In addition, direct horizontal transmission among individuals can facilitate the spread of a probiotic in a population. In this study, we tested whether the antifungal bacterium Janthinobacterium lividum could be horizontally transferred, directly or indirectly, in a laboratory experiment using Lithobates clamitans tadpoles. We evaluated the ability of J. lividumto colonize the tadpoles' skin and to persist through time using culture-dependent and culture-independent techniques. We also tested whether the addition of J. lividum affected the skin community in L. clamitans tadpoles. We found that transmission occurred rapidly by direct and indirect horizontal transmission, but indirect transmission that included a potential substrate was more effective. Even though J. lividum colonized the skin, its relative abundance on the tadpole skin decreased over time. The inoculation of J. lividum did not significantly alter the skin bacterial diversity of L. clamitans tadpoles, which was dominated by Pseudomonas Our results show that indirect horizontal transmission can be an effective bioaugmentation method. Future research is needed to determine the best conditions, including the presence of substrates, under which a probiotic can persist on the skin so that bioaugmentation becomes a successful strategy to mitigate chytridiomycosis.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.


  9 / 34 MEDLINE  
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PMID:26658253
Autor:Cloyed CS; Newsome SD; Eason PK
Endereço:Department of Biology, University of Louisville, Louisville, Kentucky 40292; 2Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131.
Título:Trophic Discrimination Factors and Incorporation Rates of Carbon- and Nitrogen-Stable Isotopes in Adult Green Frogs, Lithobates clamitans.
Fonte:Physiol Biochem Zool; 88(5):576-85, 2015 Sep-Oct.
ISSN:1537-5293
País de publicação:United States
Idioma:eng
Resumo:Stable isotope analysis is an increasingly useful ecological tool, but its accuracy depends on quantifying the tissue-specific trophic discrimination factors (TDFs) and isotopic incorporation rates for focal taxa. Despite the technique's ubiquity, most laboratory experiments determining TDFs and incorporation rates have focused on birds, mammals, and fish; we know little about terrestrial ectotherms, and amphibians in particular are understudied. In this study we used two controlled feeding experiments to determine carbon (δ(13)C) and nitrogen (δ(15)N) isotope TDFs for skin, whole blood, and bone collagen and incorporation rates for skin and whole blood in adult green frogs, Lithobates clamitans. The mean (±SD) TDFs for δ(13)C were 0.1‰ (±0.4‰) for skin, 0.5‰ (±0.5‰) for whole blood, and 1.6‰ (0.6‰) for bone collagen. The mean (±SD) TDFs for δ(15)N were 2.3‰ (±0.5‰) for skin, 2.3‰ (±0.4‰) for whole blood, and 3.1‰ (±0.6‰) for bone collagen. A combination of different isotopic incorporation models was best supported by our data. Carbon in skin was the only tissue in which incorporation was best explained by two compartments, which had half-lives of 89 and 8 d. The half-life of carbon in whole blood was 69 d. Half-lives for nitrogen were 75 d for skin and 71 d for whole blood. Our results help fill a taxonomic gap in our knowledge of stable isotope dynamics and provide ecologists with a method to measure anuran diets.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Carbon Isotopes); 0 (Nitrogen Isotopes); 7440-44-0 (Carbon); 9007-34-5 (Collagen); N762921K75 (Nitrogen)


  10 / 34 MEDLINE  
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PMID:26269462
Autor:Crespi EJ; Rissler LJ; Mattheus NM; Engbrecht K; Duncan SI; Seaborn T; Hall EM; Peterson JD; Brunner JL
Endereço:*School of Biological Sciences, Washington State University, Pullman, WA 99164, USA; erica.crespi@wsu.edu.
Título:Geophysiology of Wood Frogs: Landscape Patterns of Prevalence of Disease and Circulating Hormone Concentrations across the Eastern Range.
Fonte:Integr Comp Biol; 55(4):602-17, 2015 Oct.
ISSN:1557-7023
País de publicação:England
Idioma:eng
Resumo:One of the major challenges for conservation physiologists is to determine how current or future environmental conditions relate to the health of animals at the population level. In this study, we measured prevalence of disease, mean condition of the body, and mean resting levels of corticosterone and testosterone in a total of 28 populations across the years 2011 and 2012, and correlated these measures of health to climatic suitability of habitat, using estimates from a model of the ecological niche of the wood frog's geographic range. Using the core-periphery hypothesis as a theoretical framework, we predicted a higher prevalence and intensity of infection of Batrachochytrium dendrobatidis (Bd) and ranaviruses, two major amphibian pathogens causing disease, and higher resting levels of circulating corticosterone, an indicator of allostatic load incurred from living in marginal habitats. We found that Bd infections were rare (2% of individuals tested), while infections with ranavirus were much more common: ranavirus-infected individuals were found in 92% of ponds tested over the 2 years. Contrary to our predictions, rates of infection with ranaviruses were positively correlated with quality of the habitat with the highest prevalence at the core of the range, and plasma corticosterone concentrations measured when frogs were at rest were not correlated with quality of the habitat, the prevalence of ranavirus, or the intensity of infection. Prevalence and mean viral titers of ranavirus infection were higher in 2012 than in 2011, which coincided with lower levels of circulating corticosterone and testosterone and an extremely early time of breeding due to relatively higher temperatures during the winter. In addition, the odds of having a ranavirus infection increased with decreased body condition, and if animals had an infection, viral titers were positively correlated to levels of circulating testosterone concentration. By resolving these patterns, experiments can be designed to test hypotheses about the mechanisms that produce them, such as whether transmission of the ranavirus and tolerance of the host are greater or whether virulence is lower in populations within core habitats. While there is debate about which metrics serve as the best bioindicators of population health, the findings of this study demonstrate the importance of long-term monitoring of multiple physiological parameters to better understand the dynamic relationship between the environment and the health of wildlife populations over space and time.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.; REVIEW



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